A lighting unit utilizing a variety of light sources used in an electronic apparatus has been implemented in such a way to increase an optical efficiency by using a light source appropriate for the characteristics of each electronic apparatus.
Recently, the lighting unit for use in such an electronic apparatus may apply to various fields such as a backlight unit used in a flat panel display, an indoor light used in an indoor environment, a headlight, a fog light, a back-up lamp, a side light, a license plate light, a taillight, a stop lamp, a turn signal lamp, and a hazard flasher lamp mounted on outside of a vehicle, or an interior light for a vehicle.
However, most of these lights generally employ an approaching method in an aspect of brightness of a surface light source by applying a member such as a light guide plate used to transfer light efficiently.
In case of a vehicle lighting, especially, the recent trend is developing to make a light source an LED used to implement a high optical efficiency. In case that a vehicle lighting uses a surface light source, an LED package is increasingly used as a light source. However, when the LED package is used as a light source, it is inevitable that a large amount of light is needed or the number of optical elements forming a light emitting surface for a surface emitting is increased. Also, when a number of LED packages is applied, there are many problems such as high cost, radiation, and circuit configuration in a curved portion or a narrow space of a vehicle, so that there exists a fatal shortcoming that leads to a high cost and a low efficiency. Also, in case of a taillight of a vehicle or a light emitting place whose surface has a curvature, it is difficult to embody a uniform luminous intensity on the entire light emitting surface so that a dark portion occurs at the front and rear of the curvature portion. Additional optical elements employed to prevent the dark portion inevitably lead to an increased cost.